Background <p>Previous studies have proposed that socioeconomic status (SES) can affect postpartum depression (PPD) through the mediators of satisfaction with material needs, healthcare, maternity leave, and postpartum social support. However, empirical data to validate these propositions has been lacking. This study aims to examine if all the four mediators can significantly mediate the effects of SES on PPD, as well as to compare the effect sizes of these mediators using a parallel mediation model.</p> Methods <p>A total of 328 mothers within 1 year after childbirth completed the Socioeconomic Status Questionnaire, Met Material Needs Questionnaire, Inpatient Satisfaction with Care Questionnaire, Self-care Ability Scale for Puerperal Women, Maternity Leave Questionnaire, Questionnaire for Social Support during the Postpartum Period, and Beck Depression Inventory.</p> Results <p>The level of depression in lower-SES mothers (M = 18.38, SD = 6.88) was significantly higher than that in medium-SES mothers (M = 14.54, SD = 8.58), which was significantly higher than that in higher-SES mothers (M = 10.61, SD = 8.25). SES significantly affected satisfaction with material needs, healthcare, maternity leave, and postpartum social support. Satisfaction with material needs and postpartum social support had a significant impact on PPD, and played a significant mediating role in the relationship between SES and PPD, with mediating effect sizes of 40.0% and 30.3%, respectively. In contrast, healthcare and maternity leave did not significantly influence PPD, nor did they significantly mediate the effect of SES on PPD.</p> Conclusions <p>Postpartum social support and satisfaction with material needs are two important mediators between SES and PPD, whereas healthcare and maternity leave are two insignificant mediators in this relationship. More actions should be taken to reduce PPD in postpartum mothers, particularly those lower-SES mothers.</p>